San Juan County’s Critical Areas are environmentally sensitive natural resources that have been designated for protection and management in accordance with the requirements of the Washington Growth Management Act. Protection and management of these areas is important to the preservation of ecological functions and values of our natural environment, as well as the protection of the public health, safety and welfare of our island communities.


An aquifer is a permeable subsurface soil or rock layer that is capable of storing, transmitting and supplying ground water to wells, springs, streams or nearshore areas. Critical aquifer recharge areas are areas that have been identified as having a critical effect on aquifers and/or as being highly susceptible to contamination. A hydrologic analysis that was performed in accordance with State guidelines found that virtually all of the County is moderately or highly susceptible to contamination.

Fish and wildlife habitat conservation areas include habitat areas for birds, fish, and animals, such as shellfish areas, kelp and eelgrass beds, forage fish spawning areas, ponds, lakes and streams. These areas include lands that support endangered, threatened, and sensitive species, and species of local importance.

Habitat Conservation Areas (HCAs) are protected to:

• Ensure the continued existence of fish and wildlife populations by protecting and conserving their habitat;
• encourage the preservation of marine shorelines and natural stream functions that support fish and wildlife populations;
• preserve critical wildlife habitats so that isolated populations of species are not created and habitat fragmentation is avoided, especially along riparian corridors;
• and maintain the natural geographic distribution of fish and wildlife habitat.

Geologically hazardous areas are those areas that are susceptible to erosion, sliding, earthquake, or other geological events and are not suited to the siting of commercial, residential, or industrial development consistent with public health and safety concerns. These include landslide hazard areas, seismic hazards, mine hazards, alluvial fans, and erosion hazards areas.


Wetlands are areas inundated or saturated by surface water or ground water at a frequency or duration sufficient to support a prevalence of vegetation adapted to saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. Wetlands generally include swamps (forested), marshes (non-forested), bogs (peat) and other similar areas, and may be either freshwater or estuarine systems.

Wetlands perform a variety of beneficial functions, including:

• Habitat diversity and food chain support for fish and wildlife;
• Erosion control and shoreline stabilization;
• Maintenance of stream flows by gradually releasing stored water after floods and wet seasons;
• Storage of storm and flood waters;
• Improvement of water quality through filtration and retention of sediments, nutrients and contaminants;
• Groundwater recharge; and
• Education, scientific study, and aesthetic appreciation.

Frequently flooded areas are lands in floodplains subject to a 1 percent or greater chance of flooding in any given year. In San Juan County frequently flooded areas are generally coastal areas subject to inundation by flood waters during major storm events that are of such a magnitude that they pose a significant risk to personal property. Development activities proposed within frequently flooded areas must mitigate for flood hazards and conform to the county provisions.